Are you Leica LTM users (IIIf/IIIc/etc.) comfortable using your Leica's without an auxillary viewfinder?

I love my M3 and my DR Cron but this combination isn't really THAT compact and so I'm debating on trying a IIIf/IIIc with a collapsible Summicron (or Summitar) or maybe just getting a collapsible and sticking it on my M. My concern with the IIIf/IIIc is that the viewfinder is too poor and sticking an auxiliary viewfinder will be self defeating.

I'm not interested in much anything else.
-IIIg's seem to be bulkier and more expensive than IIIc/IIIf's...I might as well stay with an M
-CL's and most things more modern (e.g. Bessa) seem to not be as durable.
-I don't like most P&S's because I want to be able to focus and I prefer all-mechanical bodies anyways.

I have a Rollei 35 and a Kodak Retina but I can't focus accurately enough with the former and the later isn't that ergonomic.

The IIIg is still pretty compact and has a very good finder. It is an exceptionally well made camera - almost a mechanical work of art - as much so as earliest M bodies.

The Bessa's are all very well made, reliable, and durable enough for most people. The Bessa R is fairly compact and it is light - the L and T of course more so. They are lighter and more compact than Leica M's. Not sure if they accept all collapsible lenses. The Bessa bodies (with finders) have about the best finders I've seen - they best early Leica M models.

I don't have too much CL experience, but they seem OK - not that small or light - many need servicing.

The Leica IIIc_IIIf series are decent cameras, with a so-so, but usable 50mm viewfinder.

The other Leica III series have usable finders and only for 50mm frame lines. Their finders are pretty poor by modern standards and there are other bottom loaders with better finders. The Leica external 5cm finder is small, and a real work of art - fantastic on a Leica III series.